This invention is related to the coupling of hoses to metal or hard plastic fittings for a variety of purposes and for the carrying of a variety of substances, such as air, water, steam, hydraulic fluid, etc.
Many methods are well known in the art for the coupling of a flexible rubber or plastic hose to a metal or hard plastic fitting. One typical method involves the use of a barbed, interference-type fitting, wherein the metal or hard plastic fitting is formed, at the end to which the hose is to be attached, with a plurality of annular barbs which taper toward the hose end of the fitting. In such a fitting, the diameter of the barbed end of the fitting is typically of a slightly larger outer diameter than the inner diameter of the hose, such that the hose is deformed outwardly as the fitting is inserted into the open end of the hose, thereby creating the interference fit. Such fittings are well known in the prior art and are disclosed, in various configurations, in U.S. Pat. Nos. 4,453,746 (Keenan), 4,958,861 (Hamilton), 5,947,386 (Dick, et al.) and 6,270,126 B1 (Juedes) and many others.
In the Applicant""s device, a portable clothing steamer of the type shown in FIG. 1, the interference fit is used to couple the handpiece of the steamer to the hose which delivers the steam from the steam-generating unit. The handpiece is composed of a hard plastic, while the hose is composed of flexible rubber. The fitting is covered by a hard plastic molding shaped to fit the hand of a typical user, to ease the use of the handpiece. It has been found that, after period of time, the interference fitting between the hose and the tube of the handpiece becomes loose, causing the handpiece to slip off of the end of the hose. This is most likely due the stretching of the rubber hose at the interference fitting due to the movement of the handpiece as it is used by the user, or by the rubber hose losing elasticity due to the movement of high-temperature steam therethrough.
This problem can be solved through the use of a clamp which fits around the outer diameter of the hose and which is tightened, thereby clamping the hose to the plurality of annular barbs present on the piece to which the hose is coupled. Such a solution is shown in FIG. 5 of Keenan, as reference number 80. One drawback to the use of the clamp is the added cost during the manufacturing process associated with adding and tightening the clamp. The cost of adding the clamp not only includes that actual cost of the clamp, but the cost of the added time in fitting and tightening the clamp, and the cost of any tools or machinery needed to install the clamp. It would therefore be desirable to find another method of preventing the hose from slipping off of the end of the interference fit.
The solution to the problem presented herein is the addition of a plurality of protrusions present on the inner surface of the covering of the steamer handpiece. These protrusions extend in from the inner surface of the covering of the handpiece and impinge on the outer surface of the hose at the point where the hose overlays the annular barbs on the coupling. The protrusions serve to hold the hose in place by dimpling the outer surface of the hose and by pushing the hose tighter against the annular barbs of the coupling. Because the covering of the handpiece is already being installed, this solution adds no additional cost to the manufacturing process. It has been found that, for this application, the optimal configuration is six barbs arranged in two groups of thee such that they contact the outer surface of the hose on opposite sides thereof. Preferably, the barbs are staggered and contact the hose at a spacing equivalent to the spacing of the barbs of the interference fitting, such that the protrusions serve to push the inner surface of the hose into contact with the shoulders of the individual barbs of the interference fitting. Other configurations may be more optimal for other applications, and the placement and number of protrusions may be varied within the scope of the invention.